Radar leakage measurement update

ABSTRACT

A method and electronic device for updating a leakage response for leakage cancelation. The electronic device includes a radar transceiver, a memory, and a processor. The processor is configured to determine whether an object is within proximity of and within a field of view of the radar transceiver, obtain a leakage measurement for the radar transceiver in response to determining that no object is proximate to and within the field of view of the radar transceiver, and update the leakage response for leakage cancelation based on the leakage measurement.

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/810,301 filed Feb. 25, 2019, thecontents of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to addressing signal leakage inradar applications. More specifically, the present disclosure relates toopportunistic updating of radar leakage measurements for radartransceivers.

BACKGROUND

Radar can operate at various frequency bands including, but not limitedto, 6-8 GHz, 28 GHz, 39 GHz, 60 GHz, and 77 GHz. Radar operates tolocalize targets in the radar field of view in terms of azimuth (range)and/or elevation (angle) and/or velocity. For mono-static radar, thetransmitter and the receiver are installed closely together, whichresults in the transmission of a leakage signal directly from thetransmitter to the receiver. The leakage signal interferes with radardetection and ranging. Strong leakage signals can interfere with thesignals returning from a target, which can mask the target to preventdetection and/or render range estimation inaccurate. Accordingly,leakage signals can be canceled by various conventional methods toincrease the reliability of target detection and ranging.

SUMMARY

Embodiments of the present disclosure include a method, an electronicdevice, and a non-transitory computer readable medium for leakagecancelation. In one embodiment, the electronic device includes a radartransceiver, a memory, and a processor. The processor is configured todetermine whether an object is within proximity of and within a field ofview of the radar transceiver, obtain a leakage measurement for theradar transceiver in response to determining that no object is proximateto and within the field of view of the radar transceiver, and update theleakage response for leakage cancelation based on the leakagemeasurement.

In another embodiment, a method of canceling leakage includesdetermining, by an electronic device having a radar transceiver, whetheran object is within proximity of and within a field of view of the radartransceiver; obtaining a leakage measurement for the radar transceiverin response to determining that no object is proximate to and within thefield of view of the radar transceiver; and updating a leakage responsefor leakage cancelation based on the leakage measurement.

In another embodiment, an electronic device includes a non-transitorycomputer readable medium. The non-transitory computer readable mediumstores instructions that, when executed by the processor, cause theprocessor to determine, by an electronic device having a radartransceiver, whether an object is within proximity of and within a fieldof view of the radar transceiver; obtain a leakage measurement for theradar transceiver in response to determining that no object is proximateto and within the field of view of the radar transceiver; and update aleakage response for leakage cancelation based on the leakagemeasurement.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout the present disclosure. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaning“and/or”. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The phrase “at least one of,” when used with a list of items,means that different combinations of one or more of the listed items maybe used, and only one item in the list may be needed. For example, “atleast one of: A, B, and C” includes any of the following combinations:A, B, C, A and B, A and C, B and C, and A and B and C. Likewise, theterm “set” means one or more. Accordingly, a set of items can be asingle item or a collection of two or more items.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthe present disclosure. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure and its advantages,reference is now made to the following description, taken in conjunctionwith the accompanying drawings, in which like reference numeralsrepresent like parts:

FIG. 1 illustrates an electronic device according to various embodimentsof the present disclosure;

FIG. 2 illustrates a monostatic radar according to various embodimentsof the present disclosure;

FIG. 3 illustrates an example of a channel impulse response (CIR)according to various embodiments of the present disclosure;

FIG. 4 illustrates a timing diagram for radar transmission according tovarious embodiments of the present disclosure;

FIG. 5 illustrates a flowchart for leakage cancelation according tovarious embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of steps for opportunistically updating aleakage measurement according to various embodiments of the presentdisclosure;

FIG. 7 illustrates a flowchart of steps for determining validity ofleakage measurements according to various embodiments of the presentdisclosure;

FIG. 8 illustrates a flowchart for determining validity of leakagemeasurements with reference to time as a state variable according tovarious embodiments of the present disclosure;

FIG. 9 illustrates a flowchart for determining validity of leakagemeasurements with reference to temperature and humidity as statevariables according to various embodiments of the present disclosure;

FIG. 10 illustrates a flowchart for a leakage measurement updatedecision for radar-based applications according to various embodimentsof the present disclosure;

FIG. 11 illustrates a flowchart for a leakage measurement updatedecision for radar-based presence detection according to variousembodiments of the present disclosure;

FIG. 12 illustrates a flowchart for radar-based range estimation usingan updated leakage response according to various embodiments of thepresent disclosure;

FIG. 13 illustrates a flowchart for a leakage measurement updatedecision for radar-based face authentication according to variousembodiments of the present disclosure;

FIG. 14 illustrates a user interacting with an electronic device for aradar-based face authentication according to various embodiments of thepresent disclosure.

FIG. 15 illustrates a flowchart for a leakage measurement updatedecision for radar-based mood or heartbeat monitoring according tovarious embodiments of the present disclosure;

FIG. 16 illustrates a flowchart for a leakage measurement updatedecision for applications using a non-radar sensor and a radartransceiver according to various embodiments of the present disclosure;

FIG. 17 illustrates a general flowchart for a leakage measurement updatedecision for a non-radar application according to various embodiments ofthe present disclosure;

FIG. 18 illustrates a flowchart for a leakage measurement updatedecision for a non-radar application using sensors according to variousembodiments of the present disclosure;

FIG. 19 illustrates a flowchart of a process for a leakage measurementupdate decision for vision-based face authentication in a non-radarapplication according to various embodiments of the present disclosure;

FIG. 20 illustrates a flowchart of a process for a leakage measurementupdate decision for proximity sensors in a non-radar applicationaccording to various embodiments of the present disclosure;

FIG. 21 illustrates a flowchart for integrating confidence levels into aleakage measurement update decision according to various embodiments ofthe present disclosure;

FIG. 22 illustrates a flowchart for integrating a confidence leveldecision into a leakage measurement update decision according to variousembodiments of the present disclosure;

FIG. 23 illustrates a flowchart of a process for a leakage measurementupdate decision for a voice or video call application according tovarious embodiments of the present disclosure;

FIG. 24 illustrates a flowchart of a process for an alternative leakagemeasurement update decision for a voice or video call applicationaccording to various embodiments of the present disclosure; and

FIG. 25 illustrates a flowchart of a process for opportunisticallyupdating a leakage response according to various embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The figures included herein, and the various embodiments used todescribe the principles of the present disclosure are by way ofillustration only and should not be construed in any way to limit thescope of the disclosure. Those skilled in the art will understand thatthe principles of the present disclosure may be implemented in anysuitably arranged in a wired or wireless communication system.

FIG. 1 illustrates an electronic device according to various embodimentsof the present disclosure. The embodiment of the electronic device 100shown in FIG. 1 is for illustration only. Other embodiments can be usedwithout departing from the scope of the present disclosure.

As shown in FIG. 1, the electronic device 100 includes a radio frequency(RF) transceiver 110, transmit (TX) processing circuitry 115, amicrophone 120, receive (RX) processing circuitry 125, a speaker 130, aprocessor 140, an input/output (I/O) interface (IF) 145, a memory 160, adisplay 165, an input 170, and sensors 175. Non-limiting examples ofsensors 175 include inertial sensors, proximity sensors, infraredsensors, ultrasonic sensors, laser sensors, and capacitive sensors thatcan provide contextual operational data usable for opportunisticallyupdating a leakage response. The memory 160 includes an operating system(OS) 162 and one or more applications 164. The one or more applications164 can be Type 1 applications or Type 2 applications that can be usedto provide additional contextual operational data also usable foropportunistically updating a leakage response.

The transceiver 110 transmits signals to other components in a systemand receives incoming signals transmitted by other components in thesystem. For example, the transceiver 110 transmits and receives RFsignals, such as BLUETOOTH or WI-FI signals, to and from an access point(such as a base station, WI-FI router, BLUETOOTH device) of a network(such as a WI-FI, BLUETOOTH, cellular, 5G, LTE, LTE-A, WiMAX, or anyother type of wireless network). The received signal is processed by theRX processing circuitry 125. The RX processing circuitry 125 maytransmit the processed signal to the speaker 130 (such as for voicedata) or to the processor 140 for further processing (such as for webbrowsing data). The TX processing circuitry 115 receives voice data fromthe microphone 120 or other outgoing data from the processor 140. Theoutgoing data can include web data, e-mail, or interactive video gamedata. The TX processing circuitry 115 processes the outgoing data togenerate a processed signal. The transceiver 110 receives the outgoingprocessed signal from the TX processing circuitry 115 and converts thereceived signal to an RF signal that is transmitted via an antenna. Inother embodiments, the transceiver 110 can transmit and receive radarsignals to detect the potential presence of an object in the surroundingenvironment of the electronic device 100.

In this embodiment, one of the one or more transceivers in thetransceiver 110 includes is a radar transceiver 150 configured totransmit and receive signals for detection and ranging purposes. Forexample, the radar transceiver 150 may be any type of transceiverincluding, but not limited to a WiFi transceiver, for example, an802.11ay transceiver. The radar transceiver 150 includes antennaarray(s) 155 that includes transmitter 157 and receiver 159 antennaarrays. In some embodiments, the signals transmitted by the radartransceiver 150 can include, but are not limited to, millimeter wave(mmWave) signals. The radar transceiver 150 can receive the signals,which were originally transmitted from the radar transceiver 150, afterthe signals have bounced or reflected off of target objects in thesurrounding environment of the electronic device 100. The processor 140can analyze the time difference between when the signals are transmittedby the radar transceiver 150 and received by the radar transceiver 150to measure the distance of the target objects from the electronic device100.

The transmitter 157 and the receiver 159 can be fixed in close proximityto each other such that the distance of separation between them issmall. For example, the transmitter 157 and the receiver 159 can belocated within a few centimeters of each other. In some embodiments, thetransmitter 157 and the receiver 159 can be co-located in a manner thatthe distance of separation is indistinguishable. Based on contextinformation available from other applications executing on theelectronic device 100, the processor 140 execute instructions to causethe electronic device to opportunistically update leakage measurementsfor the transmitter 157 and the receiver 159 usable to cancel a leakagesignal that is transmitted from the transmitter 157 to the receiver 159.The leakage measurements can be represented by a CIR as described inmore detail in FIG. 3.

The TX processing circuitry 115 receives analog or digital voice datafrom the microphone 120 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 140.The TX processing circuitry 115 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The transceiver 110 receives the outgoing processed baseband orIF signal from the TX processing circuitry 115 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 105.

The processor 140 is also capable of executing the operating system 162in the memory 160 in order to control the overall operation of theelectronic device 100. For example, the processor 140 can move data intoor out of the memory 160 as required by an executing process. In someembodiments, the processor 140 is configured to execute the applications164 based on the OS program 162 or in response to signals received fromexternal devices or an operator. In some embodiments, the memory 160 isfurther configured to store data, such as a leakage response for leakagecancelation, which the processor 140 can utilize to cause variouscomponents of the electronic device to perform leakage cancelationindividually or cooperatively. In some embodiments, the processor 140can control the reception of forward channel signals and thetransmission of reverse channel signals by the transceiver 110, the RXprocessing circuitry 125, and the TX processing circuitry 115 inaccordance with well-known principles. In some embodiments, theprocessor 140 includes at least one microprocessor or microcontroller.

The processor 140 is also coupled to the I/O interface 145, the display165, the input 170, and the sensor 175. The I/O interface 145 providesthe electronic device 100 with the ability to connect to other devicessuch as laptop computers and handheld computers. The I/O interface 145is the communication path between these accessories and the processor140. The display 165 can be a liquid crystal display (LCD),light-emitting diode (LED) display, organic LED (OLED), active matrixOLED (AMOLED), or other display capable of rendering text and/orgraphics, such as from websites, videos, games, images, and the like.

The processor 140 can be coupled to the input 170. An operator of theelectronic device 100 can use the input 150 to enter data or inputs intothe electronic device 100. Input 150 can be a keyboard, touch screen,mouse, track-ball, voice input, or any other device capable of acting asa user interface to allow a user to interact with electronic device 100.For example, the input 150 can include voice recognition processingthereby allowing a user to input a voice command via microphone 120. Foranother example, the input 150 can include a touch panel, a (digital)pen sensor, a key, or an ultrasonic input device. The touch panel canrecognize, for example, a touch input in at least one scheme among acapacitive scheme, a pressure sensitive scheme, an infrared scheme, oran ultrasonic scheme.

The electronic device 100 can further include one or more sensors 175that meter a physical quantity or detect an activation state of theelectronic device 100 and convert metered or detected information intoan electrical signal. For example, sensor(s) 175 may include one or morebuttons for touch input, one or more cameras, a gesture sensor, an eyetracking sensor, a gyroscope or gyro sensor, an air pressure sensor, amagnetic sensor or magnetometer, an acceleration sensor oraccelerometer, a grip sensor, a proximity sensor, a color sensor, abio-physical sensor, a temperature/humidity sensor, an illuminationsensor, an Ultraviolet (UV) sensor, an Electromyography (EMG) sensor, anElectroencephalogram (EEG) sensor, an Electrocardiogram (ECG) sensor, aninfrared (IR) sensor, an ultrasound sensor, a fingerprint sensor, andthe like. The sensor(s) 175 can further include a control circuit forcontrolling at least one of the sensors included therein.

In various embodiments, the electronic device 100 may be a phone ortablet. In other embodiments, the electronic device 100 may be a robotor any other electronic device using a radar transceiver. FIG. 1. doesnot limit the present disclosure to any particular type of electronicdevice.

FIG. 2 illustrates a monostatic radar according to various embodimentsof the present disclosure. The embodiment of the monostatic radar 200shown in FIG. 2 is for illustration only and other embodiments can beused without departing from the scope of the present disclosure. Themonostatic radar 200 illustrated in FIG. 2 includes a processor 210, atransmitter 220, and a receiver 230. In some embodiments, the processor210 can be the processor 140.

In some embodiments, the transmitter 220 and the receiver 230 can be theradar transceiver 150 and connected to the transmitter 157 and receiver159 antenna arrays, respectively, included in the antenna array(s) 155.In various embodiments, the transmitter 220 and the receiver 230 areco-located using a common antenna or nearly co-located while separatebut adjacent antennas. The monostatic radar 200 is assumed to becoherent such that the transmitter 220 and the receiver 230 aresynchronized via a common time reference.

The processor 210 controls the transmitter 220 to transmit a radarsignal or radar pulse. The radar pulse is generated as a realization ofa desired “radar waveform” modulated onto a radio carrier frequency andtransmitted through a power amplifier and antenna (shown as a parabolicantenna), such as the transmitter 220, either omni-directionally orfocused into a particular direction. After the radar pulse has beentransmitted, a target 240 at a distance R from the radar 200 and withina field-of-view of the transmitted pulse will be illuminated by RF powerdensity P_(t) (in units of W/m²) for the duration of the transmission.To the first order, P_(t) is described by Equation 1:

${p_{t} = {{\frac{P_{T}}{4\pi \; R^{2}}G_{T}} = {{\frac{P_{T}}{4\pi \; R^{2}}\frac{A_{T}}{( {\lambda^{2}\text{/}4\pi} )}} = {P_{T}\frac{A_{T}}{\lambda^{2}R^{2}}}}}},$

where P_(T) is a transmit power [W], G_(T), is a transmit antenna gain[dBi], A_(T) is an effective aperture area [m²], λ is a wavelength ofthe radar signal RF carrier signal [m], and R is the target distance[m].

The transmit power density impinging onto the target surface leads toreflections depending on the material composition, surface shape, anddielectric behavior at the frequency of the radar signal. Off-directionscattered signals are generally not strong enough to be received back atthe receiver 230, so only direct reflections contribute to a detectable,received signal. Accordingly, the illuminated area or areas of thetarget with normal vectors directing back to the receiver 230 act astransmit antenna apertures with directivities, or gains, in accordancewith their effective aperture area or areas. The reflected-back powerP_(refl) is described by Equation 2:

${P_{refl} = {{{p_{t}A_{t}G_{t}} \sim {p_{t}A_{t}r_{t}\frac{A_{t}}{( {\lambda^{2}\text{/}4\pi} )}}} = {p_{t}RCS}}},$

where P_(refl) is an effective (isotropic) target-reflected power [W],A_(t) is an effective target area normal to the radar direction [m²],r_(t) is a reflectivity of the material and shape [0, . . . , 1], G_(t)is a corresponding aperture gain [dBi], and RCS is a radar cross section[m²].

As depicted in Equation 2, the radar cross section (RCS) is anequivalent area that scales proportionally to the square of the actualreflecting area, is inversely proportional to the square of thewavelength, and is reduced by various shape factors and the reflectivityof the material itself. For example, for a flat, fully reflecting mirrorof an area A_(t), large compared with λ², RCS=4π A_(t) ²/λ². Due to thematerial and shape dependency, it is difficult to deduce the actualphysical area of the target 240 based on the reflected power even if thedistance R from the target to the radar 200 is known.

The target-reflected power at the location of the receiver 230 is basedon the reflected-power density at the reverse distance R, collected overthe receiver antenna aperture area. The received, target-reflected powerP_(R) is described by Equation 3:

${P_{R} = {{\frac{P_{refl}}{4\pi R^{2}}A_{R}} = {{P_{T} \cdot {RCS}}\frac{A_{T}A_{R}}{4\pi \lambda^{2}R^{4}}}}},$

where P_(R) is the received, target-reflected power [W] and A_(R) is thereceiver antenna effective aperture area [m²]. In some embodiments,A_(R) can be the same as A_(T).

Such a radar system is usable as long as the receiver signal exhibits asufficient signal-to-noise ratio (SNR). The particular value of the SNRdepends on the waveform and detection method used. The SNR is describedby Equation 4:

${{SNR} = \frac{P_{R}}{{kT} \cdot B \cdot F}},$

where kT is Boltzmann's constant x temperature [W/Hz], B is the radarsignal bandwidth [Hz], and F is the receiver noise factor, referring tothe degradation of receive signal SNR due to noise contributions to thereceiver circuit itself.

In some embodiments, the radar signal can be a short pulse with aduration, or width, denoted by T_(P). In these embodiments, the delay τbetween the transmission and reception of the corresponding echo will beequal to τ=2R/c, where c is the speed of light propagation in themedium, such as air. In some embodiments, there can be several targets240 at slightly different distances R. In these embodiments, theindividual echoes of each separate target 240 is distinguished as suchonly if the delays differ by at least one pulse width, and the rangeresolution of the radar is described as ΔR=cΔτ/2=cT_(P)/2. A rectangularpulse of duration T_(P) exhibits a power spectral densityP(f)˜(sin(πfT_(P))/(πfT_(P)))² with the first null at its bandwidthB=1/T_(P). Therefore, the connection of the range resolution of a radarwith the bandwidth of the radar waveform is described by Equation 5:

ΔR=c/2B

Based on the reflected signals received by the receiver 230, theprocessor 210 generates a metric that measures the response of thereflected signal as a function of the distance of the target 240 fromthe radar. In some embodiments, the metric can be a CIR.

FIG. 3 illustrates an example of a CIR depicting a measured leakageresponse according to various embodiments of the present disclosure. TheCIR is a response metric based on the signals received by the receiver230. For example, the CIR is a measure of amplitude and/or phase of areflected signal as a function of distance. As shown in FIG. 3, the CIRis depicted with the delay tap index denoted on the x-axis, measuringthe distance, and the amplitude of the radar measurement [dB] denoted onthe y-axis. In a monostatic radar, for example the radar 200, that hasseparate transmitting and receiving antenna modules, a strong signal canradiate directly from the transmitter 220 to the receiver 230 causing astrong response at the delay corresponding to the separation between thetransmitter 220 and receiver 230. The strong signal radiating from thetransmitter 220 to the receiver 230 is referred to as a leakage signal.Even if the direct leakage signal from the transmitter 220 can beassumed to correspond to a single delay, the effect of the directleakage signal can still impact multiple delay taps adjacent to thedirect leakage signal.

In the measured leakage response illustrated in FIG. 3, the main leakagepeak is denoted at tap 11. In addition, taps 10 and 12 also have strongresponses, noted by the responses being greater than 20 dB above thenoise floor. Because of the additional responses such as shown at taps10 and 12, it is difficult to reliably detect and estimate the targetrange within those first few taps from the leakage taps.

FIG. 4 illustrates a timing diagram for radar transmission according tovarious embodiments of the present disclosure. In particular, FIG. 4illustrates a frame structure that divides time into frames that eachcomprises multiple bursts. Each burst includes a plurality of pulses.The timing diagram illustrated in FIG. 4 assumes an underlying pulsecompression radar system.

As illustrated in FIG. 4, each frame includes a number of bursts N,illustrated as Burst 1, Burst 2, Burst 3, up to Burst N. Each burst isformed from a plurality of pulses. For example, FIG. 4 illustrates thatBurst 1 comprises a plurality of pulses referenced as Pulse 1, Pulse 2,etc. through Pulse M.

For example, in Burst 1 a radar transceiver, such as the transmitter157, can transmit Pulse 1, Pulse 2, and Pulse M. In Burst 2, thetransmitter 157 can transmit similar pulses Pulse 1, Pulse 2, and PulseM. Each different pulse (Pulse 1, Pulse 2, and Pulse M) and burst (Burst1, Burst 2, Burst 3, etc.) can utilize a differenttransmission/reception antenna configuration, that is the active set ofantenna elements and corresponding analog/digital beamforming weights,to identify the specific pulses and bursts. For example, each pulse orburst can utilize a different active set of antenna elements andcorresponding analog/digital beamforming weights to identify specificpulses and bursts.

Following each frame, a processor, such as the processor 140, connectedto the transmitter 157 obtains radar measurements at the end of eachframe. For example, the radar measurements can be depicted as athree-dimensional complex CIR matrix. The first dimension may correspondto the burst index, the second dimension may correspond to the pulseindex, and the third dimension may correspond to the delay tap index.The delay tap index can be translated to the measurement of range ortime of flight of the received signal.

The leakage signal from the radar transmitter to the radar receiver canhinder target detection and range estimation abilities of radar,particularly for objects within a proximity of and within a field ofview of the radar transceiver. In some exemplary embodiments, objectsare within the proximity of and within the field of view of the radartransceiver when the object is less than about 20 cm from the radartransceiver. In a more particular embodiment, the objects are within theproximity of and within the field of view of the radar transceiver whenthe object is less than about 10 cm from the radar transceiver.

Cancelation of the leakage signal can overcome this issue. Pre-measuredleakage signals stored on an electronic device, such as in memory 160 ofelectronic device 100, can be used to cancel the leakage signal fromradar measurements. This approach is feasible because the leakage signalis propagated through a rigidly defined path determined by the devicehardware, which can be assumed to be constant for a relatively longduration under similar environmental conditions. Occasional update ofthe stored leakage measurement can ensure the accuracy of radar-basedsensing. So that resources are not continually being used to update aleakage measurement when inconvenient or unnecessary, novel aspects ofthe various embodiments disclosed herein are directed toopportunistically updating a stored leakage measurement when necessaryand/or when possible. For example, a stored leakage measurement that wasrecently obtained may not need to be updated and therefore can be deemedvalid. If a stored leakage measurement is no longer valid, then thestored leakage measurement can be updated only when possible. Forexample, update of a stored leakage measurement is not possible if anobject is within a proximity to and within a field of view of the radartransceiver.

Various embodiments of the present disclosure are directed to the use ofcontext information from various applications executing on theelectronic device to determine whether a stored leakage measurement isstill valid, and if not, when update of the stored leakage measurementis possible. Regardless of whether the executing applications directlyutilize radar measurements, successful operation of these applicationsis generally contingent upon the lack of objects within a proximity toand within a field of view of the radar transceiver. An exemplaryapplication that will be explained in more detail in the figures thatfollow involves radar-based face authentication. In this case, forsuccessful operation, there must be no obstacle between the radarantenna modules and the user's face, which are typically separated by adistance between 20 to 50 cm. Up-to-date leakage measurements can beextracted from the radar measurements that have yielded a desirableresult (e.g., a successful authentication). The extracted leakagemeasurement can be used to update a leakage response of a radartransceiver in an electronic device by canceling out the leakage signalof the radar measurement. The updated leakage response can then be usedfor a reliable detection and accurate ranging of targets, particularlywithin the proximity of and within a field of view of the radartransceiver.

FIG. 5 illustrates a flowchart of general operations for leakagecancelation according to various embodiments of the present disclosure.A processor can execute instructions to cause an electronic device, suchas processor 140 of electronic device 100 in FIG. 1, to undergo theoperations described in flowchart 500 for canceling the effect of theleakage signal that is transmitted directly from a transmitter to areceiver. For example, radar measurements taken in operation 502 includea leakage signal that can be canceled in operation 506 by stored leakagemeasurements obtained from operation 504. A stored leakage measurementis data describing signal strength of a set of leakage signals relativeto a delay tap index which can be attributed to the leakage signaltransmitted directly from the transmitter to the receiver of a radartransceiver. The stored leakage measurement can be represented in a CIRas shown in FIG. 3. Target detection and range estimation can beachieved in operation 508 using the radar measurements after the leakagecancellation.

The stored leakage measurements of FIG. 5 can be associated with one ormore state variables, such as a timestamp, temperature, or humiditydescribing conditions when the stored leakage measurement was obtained.Each of the state variables can be further divided into one or morecategories or ranges. For example, the stored leakage measurements couldbe stored for each temperature category (such as high, medium, low, orthe temperature could be divided into multiple bins of size N degreeseach). Then, a leakage measurement update could be done for eachtemperature category separately. Also, when the stored measurement isused to remove the leakage for the radar detection and estimation, thetemperature when the radar measurement was done can be used to selectthe appropriate stored leakage measurement to be used for the leakageremoval. Other types of information could also be used in a similarmanner. For example, the humidity is another factor that could affectthe behavior of the circuitry of the device and thus can also impact theleakage behavior, and it could be used as a part of the operatingenvironment description.

FIG. 6 illustrates a flowchart of operations for opportunisticallyupdating a leakage measurement according to a non-limiting embodiment ofthe present disclosure. A processor can execute instructions to cause anelectronic device, such as processor 140 of electronic device 100 inFIG. 1, to undergo the operations described in flowchart 600 todetermine validity of a stored leakage measurement and to update thestored leakage signal if necessary and if possible.

A state of the electronic device is identified in operation 602. Thestate of the device is based on one or more state variables, examples ofwhich can include time, temperature, and humidity. Based on the state ofthe device, the validity of a stored leakage measurement can bedetermined in operation 604. The flowcharts depicted in FIGS. 7-9 andthe related embodiments illustrate some non-limiting examples fordetermining the validity of stored leakage measurements based on statevariables.

If the stored leakage measurement is still valid, then the storedleakage measurement is not updated in operation 606. Otherwise, if thestored leakage measurement is no longer valid, as determined inoperation 604, then a determination as to whether the stored leakagemeasurement can be updated is made in operation 608. Flowchart 600proceeds to operation 610 if the stored leakage measurement cannot beupdated, or to operation 612 if the stored leakage measurement can beupdated.

There are different approaches for updating stored leakage measurementsin operation 612. For example, a simple approach is to replace thestored leakage measurement with a newly obtained leakage measurement.Another approach involves averaging, either a simple average of all pastvalid leakage measurements or a weighted average. In one embodiment, theweighted average can include all historical leakage measurements and inanother embodiment, the weighted average spans only a certain window oftime to include only a subset of historical leakage measurements. Yetanother weighted average approach could use the time-stamp of theleakage measurements to determine the age of the measurements andperform averaging weighted by the freshness of the measurements (e.g.,giving more weight to more recent leakage measurements). Note that ifthe leakage measurements are stored for different types of categories ofthe operating environment of the radar (e.g., defined by state variablessuch as temperature and/or humidity), the averaging methods described sofar could be used on the measurements belonging to each operatingenvironment category separately.

FIG. 7 illustrates a flowchart of steps for determining validity ofstored leakage measurements according to various embodiments of thepresent disclosure. A classifier can determine if a leakage update isneeded (i.e., make the validity determination) in operation 706 based ona stored state variable (S_(lk)) of a stored leakage measurement fromoperation 702 and a current state variable (S_(cu)) of the electronicdevice from operation 704. The stored state variable can be maintainedin memory 160 and compared with the corresponding state variabledetermined by one or more sensors 175 and/or applications 164. Based onthe results of the determination made in operation 706, flowchart 700proceeds to operation 708 if the stored leakage measurement is notvalid, or to operation 710 if the stored leakage measurement is stillvalid.

FIG. 8 illustrates a flowchart for determining validity of leakagemeasurements with reference to time as a state variable according tovarious embodiments of the present disclosure. A processor can make thevalidity determination in operation 806 using the stored timestamp(t_(lk)) of a stored leakage measurement from operation 802 and acurrent timestamp (t_(cu)) from operation 804. The stored state variablecan be maintained in memory 160 and compared with the correspondingstate variable determined by one or more applications 164 capable ofproviding a current timestamp. For example, in operation 806 a processorcan make a determination if the difference between the stored timestampand the current timestamp exceeds a predefined threshold value. If thedifference exceeds the predefined threshold value, then the storedleakage measurement is deemed invalid in operation 808 or valid inoperation 810.

FIG. 9 illustrates a flowchart for determining validity of leakagemeasurements with reference to temperature and humidity as statevariables according to various embodiments of the present disclosure. Aprocessor can make the validity determination in operation 910 based ona comparison of a temperature of a stored leakage measurement (T_(lk))from operation 902 and a current temperature (T_(cu)) of the electronicdevice from operation 908, and/or a comparison of a humidity of a storedleakage measurement (H_(lk)) from operation 904 and a current humidity(H_(cu)) of the electronic device from operation 906. The stored statevariable can be maintained in memory 160 and compared with thecorresponding state variable determined by one or more sensors 175capable of providing a current temperature and/or humidity.

In the non-limiting embodiment depicted in FIG. 9, a validitydetermination can be made in operation 910 if a difference between thecurrent temperature (T_(cu)) and the stored temperature (T_(lk))associated with the stored leakage measurement exceeds a temperaturethreshold, and/or if a difference between the current humidity (H_(cu))and the stored humidity (H_(lk)) associated with the stored leakagemeasurement exceeds a humidity threshold. The flowchart 900 proceeds tooperation 912 if the temperature threshold is exceeded, the humiditythreshold is exceeded, or both the temperature threshold and humiditythreshold are exceeded. The flowchart 900 proceeds to operation 914 ifneither the temperature threshold nor the humidity threshold isexceeded.

For ease of discussion, the opportunistic updating of leakagemeasurements can be separated into two different types of applications.The first type of application, which may be referred to herein as a Type1 application, is an application that uses radar measurements. Theseradar-based applications do not necessarily require target detection asin a typical radar use case. Some examples include face authenticationand gesture recognition where explicit radar detection is not required(although one can still be used). The second type of application, whichmay be referred to herein as a Type 2 application, does not use radarmeasurements. Type 2 applications can use other non-radar sensors (e.g.,a camera) or no sensor at all. Operational contextual data fromnon-radar sensors or the application itself can be used to infer whetherupdate of leakage measurement is possible (i.e., that the radarfield-of-view is clear of objects so that a new leakage measurement canbe obtained). In both Type 1 and Type 2 applications, a leakagemeasurement update decision is made based on the inference to determinewhether an object is within a proximity to and within a field-of-view ofan associated radar transceiver, which would prevent the capture of anaccurate leakage measurement.

FIG. 10 illustrates a flowchart for a leakage measurement updatedecision for radar-based applications according to various embodimentsof the present disclosure. A processor can execute instructions to causean electronic device, such as processor 140 of electronic device 100 inFIG. 1, to undergo the operations described in flowchart 1000 to arriveat the leakage measurement update decision. Generally, Type 1applications obtain and process radar measurements to generate someoperational contextual data, which is application-specific, describingthe state of the operation of the application. The operational contextdata can then be used to determine if the leakage measurement can beupdated as described in FIG. 10 and the figures that follow.

In flowchart 1000, radar measurements are obtained in operation 1002 forType 1 applications. The radar measurements can be obtained from radartransceiver 150 in FIG. 1. The radar measurements include leakagesignals transmitted directly from the radar transmitter 157 to the radarreceiver 159, as well as the signals returning to the receiver 159 froma target within a field-of-view of the radar transceiver 150.

Based on those radar measurements obtained in operation 1002, adetermination is made in operation 1004 as to whether the leakagemeasurement can be updated. If the leakage measurement can be updated,then in operation 1006 measurements corresponding to the leakage signalare extracted from the radar measurement. In a particular embodiment,the extraction is achieved by selecting the signal response(s)corresponding to small delay taps (e.g., in the range from between 0-20cm, or in the range between about 0-15 cm). These small delay taps maybe referred to in the alternative as “leakage taps”. Because leakage isthe direct transmission between the transmitter and receiver the pathlength is short and thus its primary impact is at the short-rangedistance. For this reason, to cancel the main leakage, the radarmeasurements at close range or equivalently small delay indices are ofparticular concern.

In operation 1008, the stored leakage measurement can be updated withthe extracted measurements corresponding to the leakage signal. If, atoperation 1004 a determination is made that the leakage measurementcannot be updated, then the leakage signal is not updated at operation1010.

FIG. 11 illustrates a flowchart for a leakage measurement updatedecision for radar-based presence detection according to variousembodiments of the present disclosure. The leakage measurement updatedecision can be made based, at least in part, on information from a Type1 application that employs an algorithm for processing raw radarmeasurements to detect the presence of an object in its vicinity. Theraw radar measurements include contributions from the leakage signal.The application might also have range estimation functionality that willlikely be inaccurate due to the influence of the leakage signal,particularly in the close-range distances such as distances less thanabout 20 cm, or distances less than about 10 cm. Presence detection isachieved by observing the behavior of the CIR near the leakage taps. Theleakage contribution which originates from a static source possessescertain behaviors. By detecting the deviation of the measured radarsignals, it is possible to detect the presence of an object. Variousapproaches could be used as the detection algorithm. Some examplesinclude classical signal processing algorithms and machine learningapproaches. Some example signal processing approaches could be a methodto detect the changes in the shape of the leakage CIR. Such a method cancompute some notion of distance to some stored templates of the pureleakage CIR, and if the resulting distance deviate by a certainthreshold, a target is detected; otherwise no target is detected. Someexample machine learning approaches could be any classifiers such as thek-nearest neighbor or support vector machine or even neuralnetwork-based classifiers. The classifier can be trained to recognizethe behavior of pure leakage CIR, so that it can differentiate pureleakage CIR from non-pure leakage CIR (i.e., when there are one or moretargets present).

A processor can execute instructions to cause an electronic device, suchas processor 140 of electronic device 100 in FIG. 1, to undergo theseries of operations described in flowchart 1100. In operation 1102,radar measurements for presence detection are obtained. The measurementsmay be obtained by a radar transceiver 150 from FIG. 1. A determinationis made in operation 1104 as to whether a target's presence is detected.If the target's presence is not detected, then no object is withinproximity of and within a field of view of the radar transceiver.Measurements corresponding to the leakage signal between the transmitterand the receiver are extracted in operation 1106 and used to update thestored leakage measurement in operation 1108.

If a target is detected in operation 1104, then a possibility existsthat the object could be within the proximity of and within the field ofview of the radar transceiver. Accordingly, flowchart 1100 proceeds tooperation 1110 and the stored leakage is not updated.

FIG. 12 illustrates a flowchart for radar-based range estimation usingan updated leakage response according to various embodiments of thepresent disclosure. A processor can execute instructions to cause anelectronic device, such as processor 140 of electronic device 100 inFIG. 1 to undergo the series of operations described in flowchart 1200for range estimation. In operation 1202, radar measurements for presencedetection are obtained. A determination is made in operation 1204 as towhether a target is detected. If a target is not detected, then thestored leakage measurement is updated in operation 1206 if needed. In anon-limiting embodiment, the stored leakage measurement is updated byextracting the leakage signal from the radar measurements obtained inoperation 1202. Returning back to operation 1204, if a target isdetected, then the target's range is estimated in operation 1208 usingan updated leakage response that was previously obtained.

FIG. 13 illustrates a flowchart for a leakage measurement updatedecision for radar-based face authentication according to variousembodiments of the present disclosure. Flowchart 1300 describes the useof operational context data from a radar-based face authenticationapplication for the leakage update decision. Radar measurements for faceauthentication are inputs into a face authentication algorithm and theoutput of the face authentication application contains the desiredoperational contextual data. For example, if the face authenticationapplication successfully performs a radar measurement, whether the useris authenticated or not, then it can be assumed that a face was properlycaptured in the radar measurements without any obstructing objects inthe environment positioned between the radar transceiver and the user'sface. An illustration depicting a typical use case of an electronicdevice for face authentication is depicted in FIG. 14. The radarmeasurements of the user's face contain leakage signals in the smalldelay taps that can be used for updating a leakage measurement.

Using radar measurements for face authentication obtained in operation1302, a determination is made in operation 1304 as to whether faceauthentication is successfully completed. In one embodiment, thesuccessful completion of face authentication is the authentication of auser on an electronic device executing the radar-based faceauthentication application. In another embodiment, successful completionof face authentication can be a rejection of the user's authenticationattempt based on unobstructed radar measurements.

If face authentication is successfully completed, then measurementscorresponding to the leakage signal is extracted from the radarmeasurements in operation 1306. A stored leakage measurement is updatedwith the extracted measurements in operation 1308. If faceauthentication is not successfully completed in operation 1304, then theleakage measurement is not updated in operation 1310.

FIG. 14 illustrates a user interacting with an electronic device for aradar-based face authentication according to various embodiments of thepresent disclosure. The electronic device 1400, which is an electronicdevice such as device 100 in FIG. 1, executes a radar-basedauthentication application (not shown) for authenticating user 1402. Theelectronic device 1400 is maintained a distance D away from a face ofuser 1402. Generally, the distance is between 20-50 cm, which ensuresthat objects are not present within a proximity to and within a field ofview of the electronic device 1400 (i.e., between 0-20 cm from theelectronic device).

FIG. 15 illustrates a flowchart for a leakage measurement updatedecision for radar-based mood or heartbeat monitoring according tovarious embodiments of the present disclosure. Flowchart 1500 describesthe use of operational contextual data from a radar-based mood orheartbeat monitoring application for the leakage update decision. Radarmeasurements can be used by a Type 1 application for monitoring a user'smood or heartbeat, an example of which is a mobile application formonitoring a driver for drowsiness or incapacity. Radar can be used toinfer a driver's physical state based on physiological patterns such asheartbeat, breathing, etc. In this embodiment, the mobile deviceexecuting the Type 1 application can be placed on the dashboard facingthe driver. In a typical use case, there will be no obstructing objectbetween the radar transceiver and the driver.

Flowchart 1500 begins with radar measurements for mood or heartbeatmonitoring, which are obtained in operation 1502. Using those radarmeasurements, operation 1504 determines whether leakage measurement canbe updated based on signal strength and/or Doppler. Regarding thelikelihood of clearance for leakage measurement, extra precautions canbe incorporated to ensure a better quality of the captured measurements.For example, signal strength and Doppler information can be used toprovide additional operational contextual data that can be used todetermine if the vehicle is moving. Movement in the vehicle willmanifest as vibrations in the electronic device, which aremicro-movements relative to other objects in the vehicle. By confirmingthat there is no substantial energy in the leakage tap signal innon-zero Doppler bins, it can be inferred that there is no obstructingobject near the radar transceiver and the leakage can be updated. Inother words, objects that are within a proximity of and within afield-of-view of the radar transceiver will have a reflected energylevels in the leakage taps that exceeds background levels. Conversely,the lack of objects within the proximity of and within the field-of-viewof the radar transceiver will have reflected energy in the leakage tapsthat are proportionate with background levels. The amount of energy inthe non-zero Doppler bins at the small delay taps as the inverse of theconfidence level. That is the stronger the energy, the less likely thatthe leakage can be updated. Confidence levels are discussed in moredetail in FIGS. 21 and 22 that follow.

If the leakage measurement can be updated, then a measurementcorresponding to the leakage signal is extracted in operation 1506 fromthe radar measurements used in the mood or heartbeat application.However, if the leakage measurement cannot be updated based on theresults of operation 1504, then the leakage measurement is not updatedin operation 1510.

FIG. 16 illustrates a flowchart for a leakage measurement updatedecision for applications using a non-radar sensor and a radartransceiver according to various embodiments of the present disclosure.A processor can execute instructions to cause an electronic device, suchas processor 140 of electronic device 100 in FIG. 1 to undergo theoperations described in flowchart 1600, for making an update decisionusing non-radar sensors and radar-based sensors. In a particularembodiment, the non-radar sensor is an inertial sensor that can be usedto determine movement of the electronic device, and subsequent analysisof the radar measurement from the radar transceiver can be used todetermine if a new leakage measurement can be obtained.

If the electronic device is in motion with respect to its surrounding,then the Doppler information and the signal strength can be used todetect if there is any obstacle in its vicinity. The device motion couldalso be inferred from the Type 1 application usage without usinginertial sensors as described in more detail in FIG. 15. Since thedevice is in motion with respect to its immediate surrounding, if thereis an obstructing object in the vicinity of the radar antenna module,then the reflection from this object will possess non-zero Doppler. Theleakage being the direct signal from the radar transmit antenna to thereceive antenna which are rigidly installed on the device will be staticwith respect to each other. The leakage signal will fall into the zeroDoppler bin. Thus, by confirming that there is no substantial energy inthe leakage taps signal in non-zero Doppler bin, it can be inferred thatthere is no obstructing object near the radar transceiver and theleakage can be updated. Note that in this case one can use the amount ofenergy in the non-zero Doppler bins at the small delay taps as theinverse of the confidence level. That is the stronger the energy, theless likely that the leakage can be updated, a fact that can be usedduring the calculation of confidence levels.

Flowchart 1600 begins with obtaining input from one or more sensors inoperation 1602. Using the sensor input, operation 1604 determineswhether the device is in motion. If the device is not in motion, thenthe leakage update measurement is not updated in operation 1606.However, if the device is in motion, then radar measurements areobtained in operation 1608 and the flowchart proceeds to operation 1610where a determination is made as to whether signal strength and Dopplercan be used to infer if a leakage measurement can be updated. If signalstrength and Doppler can be used to infer that the leakage measurementcan be updated, then the flowchart proceeds to operation 1612 wheremeasurements corresponding to the leakage signal is extracted from theradar measurements. The leakage measurement is updated in operation1614. However, if at operation 1610 a determination is made that signalstrength and Doppler can be used to infer that the leakage measurementcannot be updated, then the update leakage measurement is not updated inoperation 1616.

FIG. 17 illustrates a general flowchart for a leakage measurement updatedecision for a non-radar application according to various embodiments ofthe present disclosure. A processor can execute instructions to cause anelectronic device, such as processor 140 of electronic device 100 inFIG. 1, to undergo the series of steps described in flowchart 1700 tomake the leakage measurement update decision.

Operational contextual data obtained in operation 1702 can be used tomake a leakage measurement update decision in operation 1704. In someembodiments the Type 2 application uses non-radar sensors, such asproximity sensors and inertial sensors, to obtain operational contextualdata, and in other embodiments the operational contextual data isderived directly from the execution of the application. In either event,if the leakage measurement can be updated, then a radar leakagemeasurement is performed in operation 1706. The radar leakagemeasurement is performed by activating the radar transceiver to performa set of radar measurements that can be processed to obtain leakagemeasurements to update stored leakage measurements in operation 1708. Ifthe leakage measurements cannot be updated in operation 1704, then theleakage measurements are not updated in operation 1710.

FIG. 18 illustrates a flowchart for a leakage measurement updatedecision for a non-radar application using sensors according to variousembodiments of the present disclosure. A processor can executeinstructions to cause an electronic device, such as processor 140 ofelectronic device 100 in FIG. 1, to undergo the series of stepsdescribed in flowchart 1800 to make the leakage measurement updatedecision. Sensor measurements for a Type 2 application are obtained inoperation 1802. The sensor measurements can be captured directly fromone or more sensors or derived from data captured by the one or moresensors.

In operation 1804 a determination is made as to whether the leakagemeasurement can be updated based on the sensor measurements. If theleakage measurement can be updated, then a radar leakage measurement isperformed in operation 1806. The radar leakage measurement is performedby activating the radar transceiver to perform a set of radarmeasurements that can be processed to obtain leakage measurements toupdate stored leakage measurements in operation 1808. If the leakagemeasurements cannot be updated in operation 1804, then the leakagemeasurements are not updated in operation 1810.

FIG. 19 illustrates a flowchart of a process for a leakage measurementupdate decision for vision-based face authentication in a non-radarapplication according to various embodiments of the present disclosure.A processor can execute instructions to cause an electronic device, suchas processor 140 of electronic device 100 in FIG. 1, to undergo theseries of steps described in flowchart 1900 to make the leakagemeasurement update decision based on a successful image capture. Inparticular, if a user's face is successfully captured, regardless ofwhether the user was actually authenticated, then an inference can bemade that no objects are present between the electronic device and theuser's face. This also means that the environment near the radartransceiver is clear for the leakage measurement. In some embodiments,the result of the vision-based authentication application can be afactor for consideration in a confidence level determination. Forexample, a successful authentication may be weighted higher than anunsuccessful authentication because an unsuccessful authentication couldbe attributed to additional factors, such as an unintended andundetected obstruction by a user's hand or fingers.

To reduce or eliminate obstructions by a user's hand or fingers,additional sensor data can be captured and used to determine thelocation of the user's hand or fingers. For example, capacitive touchsensors can be used to detect grip, or infrared-based proximity sensorsnear the radar transceiver can be used. The sensor data can beincorporated into the computation of a confidence level as will bedescribed in FIGS. 21 and 22.

Returning to flowchart 1900, the process begins in step 1902 bycapturing a camera image for a vision-based face authenticationapplication. A determination is made as to whether the image capture wassuccessful in step 1904. If the image capture was successful, then aradar leakage measurement is performed in step 1906 and the storedleakage measurement update is updated in step 1908. However, if at step1904 a determination is made that the image capture was not successful,then the process continues to step 1910 and the stored leakagemeasurement update is not updated.

While the exemplary embodiment described in FIG. 19 is related to faceauthentication, the steps of flowchart 1900 can be generally applied toother forms of biometric authentication, such as iris sensorauthentication and fingerprint authentication, where operationalcontextual data obtained in step 1902 can be used to infer that there isno object in the vicinity of the radar transceiver for the purpose ofleakage measurement.

FIG. 20 illustrates a flowchart of a process for a leakage measurementupdate decision for proximity sensors in a non-radar applicationaccording to various embodiments of the present disclosure. A processorcan execute instructions to cause an electronic device, such asprocessor 140 of electronic device 100 in FIG. 1, to undergo the seriesof steps described in flowchart 2000. In addition, sensors 175 caninclude one or more proximity sensors capable of capturing sensor datausable for making an update decision. Examples of proximity sensorsinclude infrared, ultrasonic, laser, or capacitive based sensors or anyother types of proximity sensing based on touch or hand grip, and evenadvanced methods like using image processing on camera image to identifyobjects and measure their distances.

Proximity sensor data is obtained in step 2002 and used to make adetermination if objects are in a vicinity of the radar transceiver instep 2004. If objects are not in the vicinity of the radar transceiver,then a radar leakage measurement can be performed in step 2006 asdescribed in earlier embodiments. A stored leakage measurement can beupdated in step 2008 using the results of the radar leakage measurementbefore the process terminates. If a determination is made that an objectis within the vicinity of the radar transceiver in step 2004, then theleakage measurement is not updated in step 2010 and the processterminates.

FIG. 21 illustrates a flowchart for integrating confidence levels into aleakage measurement update decision according to various embodiments ofthe present disclosure. A confidence level is a set of computed valuesthat can be used to weight inputs to the leakage measurement updateprocedure. The confidence level can be computed by a processor in anelectronic device, such as processor 140 of electronic device 100 inFIG. 1 from data captured by one or more sensors 175 or data originatingfrom one or more of the applications 164 as previously discussed.Different approaches could be used to perform a leakage measurementupdate based on the confidence level. One example is to performaveraging weighted by the confidence level. Another possibility is toperform the averaging using weights computed using both the confidencelevel and the freshness of the measurement (e.g., determined from therecorded timestamp).

In operation 2102, radar measurements are obtained for a Type 1application. A confidence level can be computed in operation 2104 basedon the radar measurements and input into the leakage measurement updateprocedure of operation 2108, which also takes into consideration a radarmeasurement corresponding to the leakage signal that is extracted inoperation 2106.

While the flowchart in FIG. 21 is described relative to a Type 1application, contextual operational data can be captured from Type 2applications for use in computing a confidence level that can be used inmaking a leakage measurement update decision. For example, a confidencelevel can be computed for the vision-based face authenticationapplication described in FIG. 19, which takes into consideration notonly that a successful image was captured for face authentication, butalso whether the result of the face authentication was successful ornot. A successful authentication may be given a higher confidence levelthan an unsuccessful authentication.

FIG. 22 illustrates a flowchart for integrating a confidence leveldecision into a leakage measurement update decision according to variousembodiments of the present disclosure. The leakage measurement updatedecision combines a soft decision and a hard decision based on theconfidence level. The confidence level can be computed by a processor inan electronic device, such as processor 140 of electronic device 100 inFIG. 1 from data captured by one or more sensors 175 or data originatingfrom one or more of the applications 164 as previously discussed.

In operation 2202, radar measurements are obtained for a Type 1application. A confidence level is computed in operation 2204 based onthose radar measurements. In operation 2206, a determination is made asto whether the confidence level exceeds a threshold. If the confidencelevel exceeds the threshold, then in operation 2208 a measurement isextracted from the radar measurement that corresponds to the leakagesignal. In operation 2210, the stored leakage measurement is updated.However, if at operation 2206 the determination is made that theconfidence level does not exceed the threshold, then in operation 2212the stored leakage measurement is not updated.

While the flowchart in FIG. 22 is described relative to a Type 1application, contextual operational data can be captured from Type 2applications for use in computing a confidence level that can be used inmaking a leakage measurement update decision. For example, a confidencelevel can be computed for the vision-based face authenticationapplication described in FIG. 19. In addition, confidence levels can beincorporated into the Type 2 applications discussed in FIGS. 23 and 24which use contextual operational data derived from voice or video callapplications.

FIG. 23 illustrates a flowchart of a process for obtaining a leakagemeasurement update decision for a voice or video application accordingto an illustrative embodiment. The process can be implemented in acommunication-enabled electronic device, such as a phone, a tablet, or asmart watch. Additionally, the process proceeds under the assumptionthat calls accepted while the electronic device is not in hands-freemode will be brought towards the user's face or suspended in midair bythe user's hand so that the call can be conducted on speakerphone. Acondition that hands-free mode is not used reduces the likelihood thatthe call might be accepted while the electronic device is maintained ina pocket.

The process starts when a call for a voice or video application isreceived in step 2302. A determination is made in step 2304 as towhether the call is accepted without hands-free mode. If the call isaccepted without hands-free mode, then a radar leakage measurement isperformed in step 2306. A stored leakage measurement is updated with thenew radar leakage measurement in step 2308 and the process ends.Returning to step 2304, if a determination is made that the call isaccepted without hands-free mode, then the stored leakage measurement isnot updated in step 2310 and the process ends.

In another embodiment, a rejection of the call without hands-free modeactive could also be used to trigger the radar leakage measurement onthe assumption that the user would be holding the electronic device insuch a manner that would not introduce an object within the proximity ofand within a field of view of the radar transceiver.

In a variation of these embodiments, a time delay can be imposed afteracceptance of the call before allowing performing the radar leakagemeasurement to ensure that the device is in midair without anyobstruction within the proximity of the radar transceiver when theleakage measurement is captured. In yet another variation, a time windowcan be imposed for performing the radar leakage measurement in step 2306to ensure that the leakage measurement is not obtained when theelectronic device is proximate to or against a user's face.

In another variation of the embodiment described in FIG. 23, othernon-radar applications can be substituted in place of the voice/videoapplication as long as the other non-radar applications require a userto hold the electronic device in a particular position that could beused to infer that no objects are within a proximity of and within afield of view of a radar transceiver. For example, some gamingapplications may require a user to place fingers into a position thatdoes not obstruct the radar antenna module(s).

FIG. 24 illustrates a flowchart of a process for an alternative leakagemeasurement update decision for a voice or video call applicationaccording to another illustrative embodiment. The process can beimplemented in a communication-enabled electronic device, such as aphone, a tablet, or a smart watch, with hands-free mode active.Hands-free mode is active when the electronic device is connected to auser by wired or wireless headphones, which allows a user to accept orreject the call indirectly without regard to the position or location ofthe electronic device. For example, a user can accept a call with thephone in a pocket or face-down with the radar antenna module blocked.Additional contextual data may be necessary to determine whether theradar leakage measurement should be performed. Examples of contextualdata can include data from proximity sensors, light detection sensors,positioning sensors that can be used to reduce the likelihood that radarleakage measurements will be performed when one or more objects arewithin a proximity to and within a field of view of the radartransceiver.

The process described in flowchart 2400 starts when a call for a voiceor video application is received in step 2402. In step 2404 adetermination is made as to whether the call is accepted with hands-freemode active. If the call is accepted with hands-free mode active, aradar leakage measurement is performed in step 2406 if contextual datapermits. Thereafter, the stored leakage measurement is updated in step2408 and the process terminates. If at step 2404 a determination is madethat the call is not accepted with hands-free mode active, then theprocess does not update the leakage measurement in step 2410 and theprocess terminates.

Confidence levels can also be computed for the embodiments described inFIGS. 23 and 24. For example, positional sensors, light sensors, orproximity sensors providing operational contextual data consistent withan electronic device being present in a pocket or facedown on a surfacecan be used to compute a confidence level that disfavors the update of astored leakage measurement update.

FIG. 25 is a flowchart of a process for opportunistically updating aleakage response according to various embodiments of the presentdisclosure. A processor can execute instructions to cause an electronicdevice, such as processor 140 of electronic device 100 in FIG. 1, toundergo the steps described in flowchart 2500 to opportunisticallyupdate a leakage response.

The process begins in step 2502 by making a determination as to whethera change in at least one state variable is detected. The change in thestate variable can be used to identify whether a stored leakagemeasurement associated with the at least one state variable is stillvalid. Non-limiting examples of state variables can include time,temperature, humidity, or any other device-related state that can affectradar transmissions in an electronic device. In some embodiments, thechange in the at least one state variable is determined by identifyingany change in the state variable. In other embodiments, the change instate variable may be a change that exceeds some threshold value. Forexample, the change in state variable may be the passage of a discreteamount of time, or a temperature that changes by more than a certainnumber of degrees or by a certain percent.

If no change has been detected in step 2502, then update of a storedleakage response is unnecessary and the process returns to the start. Ifa change in the at least one state variable has been detected, then instep 2504 a determination is made as to whether an object is within aproximity of and within a field-of-view of a radar transceiver. If anobject is within the proximity of and within a field-of-view of theradar transceiver, then the radar signals within the leakage taps cannotbe accurately attributable to either the leakage signal or the objectwithin the proximity of the field-of-view of the radar transceiver.Accordingly, the process returns to the start.

If an object is not within the proximity of nor within the field-of-viewof the radar transceiver, then a leakage measurement is obtained in step2506. The leakage measurement can be obtained in any number of ways asdescribed in earlier embodiments. For example, the leakage measurementcan be obtained by extracting a set of signals from a radar measurementcaptured during the execution of Type 1 applications, or by activatingthe radar transceiver to perform a set of radar measurements that can beprocessed to obtain leakage measurements after or during the executionof a Type 2 application.

In step 2508, the leakage response is updated based on the leakagemeasurement. The updating can be a simple replacement or can incorporateaverages as described earlier. In addition, the updating can incorporateconfidence levels as previously described. After the leakage response isupdated, the process terminates.

As previously discussed in earlier embodiments, when the process offlowchart 2500 is applied to some Type 1 applications, the step ofdetermining whether the object is within the proximity of and within thefield of view of the radar transceiver involves performing a successfulradar-based measurement on a target located outside of the proximity ofthe radar transceiver, and the step of obtaining the leakage measurementincludes extracting signals from the successful radar-based measurementcorresponding to a set of leakage taps.

As previously discussed in earlier embodiments, when the process offlowchart 2500 is applied to some Type 1 applications that have accessto operational contextual data that includes Doppler data, the step ofdetermining whether the object is within the proximity of and within thefield of view of the radar transceiver includes confirming thatreflected energy from within the proximity of the radar transceiver isproportionate with background levels.

As previously discussed in earlier embodiments, when the process offlowchart 2500 is applied to some Type 2 applications, the step ofdetermining whether the object is within the proximity of and within thefield of view of the radar transceiver includes performing a successfulnon-radar, sensor-based measurement on a target located outside of theproximity of the radar transceiver, and the step of obtaining theleakage measurement includes measuring a leakage signal between atransmitter and a receiver of the radar transceiver.

As previously discussed in earlier embodiments, when the process offlowchart 2500 is applied to some Type 2 applications with access tooperational contextual data from one or more proximity sensors, the stepof determining whether the object is within the proximity of and withinthe field of view of the radar transceiver includes determining, with anon-radar, proximity sensor that a target is not detected within theproximity of the radar transceiver, and the step of obtaining theleakage measurement includes measuring a leakage signal between atransmitter and a receiver of the radar transceiver.

As previously discussed in earlier embodiments, when the process offlowchart 2500 is applied to some Type 2 applications without access tooperational contextual data from sensors, the step of determiningwhether the object is within the proximity of and within the field ofview of the radar transceiver includes receiving a user input by theelectronic device, the user input being correlated with an absence ofany objects within the proximity of the radar transceiver. Examples ofuser input were described in more detail in FIGS. 23 and 24 and caninclude accepting or rejecting a voice or video call when the electronicdevice is not operating in hands-free mode. Another example of userinput can be the movement of phone in three-dimensional space, such aswhen a user brings a phone towards the user's ear. In addition, the stepof obtaining the leakage measurement further comprises measuring aleakage signal between a transmitter and a receiver of the radartransceiver.

None of the description in this application should be read as implyingthat any particular element, step, or function is an essential elementthat must be included in the claim scope. Moreover, none of the claimsis intended to invoke 35 U.S.C. § 112(f) unless the exact words “meansfor” are followed by a participle.

What is claimed is:
 1. An electronic device comprising: a radartransceiver; a memory configured to store data; and a processor operablyconnected to the radar transceiver, the processor configured to:determine whether an object is within proximity of and within a field ofview of the radar transceiver; obtain a leakage measurement for theradar transceiver in response to determining that no object is proximateto and within the field of view of the radar transceiver; and update aleakage response for leakage cancelation based on the leakagemeasurement.
 2. The electronic device of claim 1, wherein the processoris further configured to: detect a change in at least one state variableof the electronic device; and determine whether the object is within theproximity of and within the field of view of the radar transceiver bydetermining whether the object is within the proximity of and within thefield of view of the radar transceiver in response to detecting thechange in the at least one state variable.
 3. The electronic device ofclaim 1, wherein the processor is configured to: determine whether theobject is within the proximity of and within the field of view of theradar transceiver by performing a successful radar-based measurement ona target located outside of the proximity of the radar transceiver, andobtain the leakage measurement by extracting signals from the successfulradar-based measurement corresponding to a set of leakage taps.
 4. Theelectronic device of claim 1, wherein the processor is configured to:determine whether the object is within the proximity of and within thefield of view of the radar transceiver by confirming that reflectedenergy from within the proximity of the radar transceiver isproportionate with background levels.
 5. The electronic device of claim1, wherein the processor is configured to: determine whether the objectis within the proximity of and within the field of view of the radartransceiver further by performing a successful non-radar, sensor-basedmeasurement on a target located outside of the proximity of the radartransceiver, and obtain the leakage measurement by measuring a leakagesignal between a transmitter and a receiver of the radar transceiver. 6.The electronic device of claim 1, wherein the processor is configuredto: determine whether the object is within the proximity of and withinthe field of view of the radar transceiver by determining, with anon-radar, proximity sensor that a target is not detected within theproximity of the radar transceiver, and obtain the leakage measurementby measuring a leakage signal between a transmitter and a receiver ofthe radar transceiver.
 7. The electronic device of claim 1, wherein theprocessor is configured to: determine whether the object is within theproximity of and within the field of view of the radar transceiver byreceiving a user input by the electronic device, wherein the user inputis correlated with an absence of any objects within the proximity of theradar transceiver, and obtain the leakage measurement by measuring aleakage signal between a transmitter and a receiver of the radartransceiver.
 8. A method for updating a leakage response, the methodcomprising: determining, by an electronic device having a radartransceiver, whether an object is within proximity of and within a fieldof view of the radar transceiver; obtaining a leakage measurement forthe radar transceiver in response to determining that no object isproximate to and within the field of view of the radar transceiver; andupdating the leakage response for leakage cancelation based on theleakage measurement.
 9. The method of claim 8, further comprisingdetecting a change in at least one state variable of the electronicdevice; and wherein determining whether the object is within theproximity of and within the field of view of the radar transceivercomprises determining whether the object is within the proximity of andwithin the field of view of the radar transceiver in response todetecting the change in the at least one state variable.
 10. The methodof claim 8, wherein determining whether the object is within theproximity of and within the field of view of the radar transceiverfurther comprises performing a successful radar-based measurement on atarget located outside of the proximity of the radar transceiver, andwherein obtaining the leakage measurement further comprises extractingsignals from the successful radar-based measurement corresponding to aset of leakage taps.
 11. The method of claim 8, wherein determiningwhether the object is within the proximity of and within the field ofview of the radar transceiver further comprises confirming thatreflected energy from within the proximity of the radar transceiver isproportionate with background levels.
 12. The method of claim 8, whereindetermining whether the object is within the proximity of and within thefield of view of the radar transceiver further comprises performing asuccessful non-radar, sensor-based measurement on a target locatedoutside of the proximity of the radar transceiver, and wherein obtainingthe leakage measurement further comprises measuring a leakage signalbetween a transmitter and a receiver of the radar transceiver.
 13. Themethod of claim 8, wherein determining whether the object is within theproximity of and within the field of view of the radar transceiverfurther comprises determining, with a non-radar, proximity sensor that atarget is not detected within the proximity of the radar transceiver,and wherein obtaining the leakage measurement further comprisesmeasuring a leakage signal between a transmitter and a receiver of theradar transceiver.
 14. The method of claim 8, wherein determiningwhether the object is within the proximity of and within the field ofview of the radar transceiver further comprises receiving a user inputby the electronic device, wherein the user input is correlated with anabsence of any objects within the proximity of the radar transceiver,and wherein obtaining the leakage measurement further comprisesmeasuring a leakage signal between a transmitter and a receiver of theradar transceiver.
 15. A non-transitory, computer-readable mediumstoring instructions that, when executed by a processor of an electronicdevice, cause the electronic device to: determine, by the electronicdevice, whether an object is within proximity of and within a field ofview of a radar transceiver of the electronic device; obtain a leakagemeasurement for the radar transceiver in response to determining that noobject is proximate to and within the field of view of the radartransceiver; and update a leakage response for leakage cancelation basedon the leakage measurement.
 16. The non-transitory, computer-readablemedium of claim 15, further storing instructions that, when executed bythe processor, cause the electronic device to: detect a change in atleast one state variable of the electronic device; and determine whetherthe object is within the proximity of and within the field of view ofthe radar transceiver by determining whether the object is within theproximity of and within the field of view of the radar transceiver inresponse to detecting the change in the at least one state variable. 17.The non-transitory, computer-readable medium of claim 15, furtherstoring instructions that, when executed by the processor, cause theelectronic device to: determine whether the object is within theproximity of and within the field of view of the radar transceiver byperforming a successful radar-based measurement on a target locatedoutside of the proximity of the radar transceiver, and obtain theleakage measurement by extracting signals from the successfulradar-based measurement corresponding to a set of leakage taps.
 18. Thenon-transitory, computer-readable medium of claim 15, further storinginstructions that, when executed by the processor, cause the electronicdevice to: determine whether the object is within the proximity of andwithin the field of view of the radar transceiver further by performinga successful non-radar, sensor-based measurement on a target locatedoutside of the proximity of the radar transceiver, and obtain theleakage measurement by measuring a leakage signal between a transmitterand a receiver of the radar transceiver.
 19. The non-transitory,computer-readable medium of claim 15, further storing instructions that,when executed by the processor, cause the electronic device to:determine whether the object is within the proximity of and within thefield of view of the radar transceiver by determining, with a non-radar,proximity sensor that a target is not detected within the proximity ofthe radar transceiver, and obtain the leakage measurement by measuring aleakage signal between a transmitter and a receiver of the radartransceiver.
 20. The non-transitory, computer-readable medium of claim15, further storing instructions that, when executed by the processor,cause the electronic device to: determine whether the object is withinthe proximity of and within the field of view of the radar transceiverby receiving a user input by the electronic device, wherein the userinput is correlated with an absence of any objects within the proximityof the radar transceiver, and obtain the leakage measurement bymeasuring a leakage signal between a transmitter and a receiver of theradar transceiver.